Dental alloy and process of making the same



. 2c The usual dental alloy of Patented Feb. 23, T92.

CLARENCE C. VOGT, F PITTSBURGH, PENNSYLVANIA, ASSIGNOE T0 LEE S. SMITH SON MANUFAOTURING COMPANY, 'TION (OF PENNSYLVANIA.

OF PITTSBURGH, PENNSYLVANIA, A. CORZPORA- DENTAL ALLOY AND PROCESS OF MAKING THE SAME.

No Drawing.

To all whom it may concern:

Be it known that l, CLARENCE C. Voc'r, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny 5 and State of Pennsylvania, have invented a new and useful .lmprovement in Dental Alloys and Processes of Making the Same, of which the following is a full, clear, and

I exact description.

The present invention relates to dental alloys and the process of making the same. The so called amalgam or silver dental fillings are made of an alloy of silver and tin usually containing small percentages of copper and zinc, mixed with mercury to form an amalgam. The alloy is of course furnished to the dentist in a comparatively finely ground condition, to be mixed with the mercury and applied to the tooth cavity.

the better class follows rather closely the so called Black formula, which is'silver 67 parts, tin 27 parts, copper 5 parts, and zinc one part.

Slight changes in percentage may be made,

but the usual proportion runs from 65 to 68 parts of silver and to 28 parts of tin.

The fillings made from this alloy possess a considerable resistance to crushing, but are comparatively weak against shearing strains, so that the fillin s are liable to break out of the teeth when they are exposed to shearing strains. The weakness to shearing strains is apparently due to a low tensile strength compared with the compression strength of the amalgam made from the alloy.

l have discovered that the shearing strength, the toughness and hardness of the amalgam made from dental alloys of this class can be greatly increased by the addition of a small proportion of one or more of the rare metals which are used for hardening and toughening steel-such as chromium, vanadium, manganese, tungsten, molybdenum, or tantalum. The proportion of the 5 rare metal preferably does not exceed about three per cent. Usually about one to two per cent of the rare metal is employed. These metals possess the remarkable quality of considerably increasing the shearing strength, the toughness and hardness of amalgam fillings made from the alloy. These metals may be added in a small percentage to an allo made in substantial accordanw with the lack formula, or the amount of copper Application filed December 26, 1922. Serial No. 609,096.

and zincand particularly copper-may be reduced in proportion to the percentage of the hardening rare metal employed.

The solubility of these rare metals in silver is so small that they are introduced into the silver alloy by an indirect method. I have found that it is possible to introduce them by combining the particular rare metal or metals with copper and. then melting the copper alloy with the silver and tin in the proper proportions. In some cases, it is advantageous to combine the copper alloy first with the silver, and after these are thoroughly mixed, to add the proper quantity of tin at a second heating or melting.

The present invention is not limited to the details above described, but the invention may be otherwise embodied within the scope of the following claims.

1 claim: I

l. A. dental alloy containing silver and tin in amounts which will readily amalgamate with mercury to form a suitable hardening dental amalgam, together with a minor proportion of tungsten, substantially as described.

2. A dentalalloy containing silver and tin in amounts which will readily amalgamate with mercury to form a suitable hardening dental amalgam, together with a minor proportion of a metal of the sixth group of the periodic system which has a toughening efi'ect upon the amalgam, substantially as described.

3. A. dental alloy containing silver and tin in amounts which will readily amalgamate with mercury to form a suitable hardening dental amlgam, together with a minor proportion of one of the metals of the fifth,

sixth or seventh groups of the periodic sys-- tem employed for the hardenin and toughening of steel which has a toug ening effect upon the amalgam, substantially as" described.

4:. A dental alloy containin silver and tin in amounts which will readi y amalgamate with mercury to form a suitable hardening dental amalgam, together with. a minor pro-- portion of one of the metals employed for the hardening and toughening of. steel which has a toughening effect upon the amalgam, substantially as described.

5. The process of making a dental alloy containing silver, tin and copper, which con llll sists in alloying with the copper a metal which has a toughening effect on an amalgam made from the alloy, and thereafter incorporating the thus alloyed copper with the silver and tin, substantially as described.

6. The process of making a dental alloy containing silver, tin and copper which consists in alloying With the copper a metal diflicultly soluble in the silver, and incor porating-the thus alloyed copper with the silver and tin, substantially as described.

7. The process of making a dental alloy containing silver, tin, and copper, which consists in alloying tungsten with the copper and thereafter incorporating the thus alloyed copper with silver and tin, substan- ,tially as described.

\ 8. The process of making a dental alloy containing silver, tin and copper, which consists in alloying with the copper a metal ot the sixth group of the periodic system which has a toughening efiect on an amalgam made from the alloy, and thereafter incorporating the thus alloyed copper with the silver and tin, substantially as described.

In testimony whereof I have hereunto set in hand.

y CLARENCE C. VOGT. 

